I can think of many words and letters to describe VC-1, but the most appropriate are “PITA”.
Most of us (around here) eradicate VC-1 on arrival - by encoding it to something else. Yes, it’s painful, considering it’s a Single Thread Operation with VC-1, but that’s better than having to deal with that crap every time it plays on something.
Roku Ultra —> VC-1 ----> Transcode City (and not the nice part of town).
I do this at 3750Kbps and can’t tell the difference, but I’m using the eyeballs in my head - they won’t work at your house. Adjust as necessary.
I can tell ya, if you’re so inclined, you could make an HEVC Main 10 Version at 3750Kbps - it may take a while (just shy of an eternity), but you’ll be hard pressed to see the difference:
AN HEVC Main 10 from a 4K source - will look better than the version you have now - if you can get your hands on such a thing (I’ve probably been stumbling over them all week).